Thyratron counting circuit



Nov. 22, 1955 w. P. OVERBECK 2,724,789

THYRA'IRON COUNTING CIRCUIT Filed Nov. 30, 1945 OUTPUT INVENTOR WILCOX P. OVERBECK QW W ATTORNEY United States Patent-O THYRATRON COUNTING CIRCUIT Wilcox P. Overbeck, Richland, Wash., assignor to the United States of America as represented by the Secretary of the Navy This invention relates to an electronic counting circuit and particularly to one including a pulsing circuit.

In my application Serial No. 332,853 filed May 1, 1940, now Patent No. 2,404,918, is disclosed a number of counting systems. These counting systems are adapted to indicate the number of electric impulses which have been applied to their input circuits. The present invention constitutes an improvement over these systems in the use of a pulsing circuit which includes a thyratron tube. This tube as used is normally in the non-conducting state, but is rendered conducting upon application of an electrical impulse to its grid. One of the characteristics of these'counting systems is that they produce negative pulses in their pulse line which are utilized to return the thyratron tube of the pulsing circuit to its non-conducting state and be once more ready for the next impulse. The addition of this pulsing circuit insures impulses of a similar and desired shape being applied to the counting system independent of the shape of the impulses applied to the pulsing circuit.

It is accordingly a principal object of this invention to provide a counting system as disclosed in the above-mentioned application with a pulsing circuit to render the system independent of the shape of the applied impulse.

Reference is now made to the accompanying drawing where a circuit diagram of an embodiment of my invention is disclosed.

A plurality of trigger tubes 0, 1, 9 have their anodes maintained at a positive potential with respect to the cathode and their grids at a negative potential. This is accomplished by applying a positive and negative direct voltage to terminals 10 and 11 respectively. These tubes are of the thyratron type, being gas filled and adapted to become conducting upon application of a positive impulse to the grid and to become non-conducting upon reduction of the anode voltage below a minimum. The values of plate resistors 12 and the grid and plate potentials are so chosen that each tube has two conditions of stabilityone in the conducting state and the other in the non-conducting state. That is, each tube will remain either conducting or non-conducting until a potential is applied to the anode or grid to change this condition. It is to be noted that the embodiment disclosed is intended to include ten of these trigger tubes, the space adjacent the dotted lines being intended to include tubes 2 through 8 and associated circuits (not shown).

The pulsing circuit includes tube P, also of the tyratron type. Tube P has-its anode and grid biased respectively positively and negatively with reference to its cathode as has each of tubes 0, 1, 9. The impulses of the series to be counted are applied at terminal 13. In the embodiment shown these impulses must be positive. With tube P in the non-conducting state, when a positive impulse of sufiicient magnitude is impressed on terminal 13, which will appear as a positive impulse at the grid of tube P, tube P will be converted to the conducting state. The anode of tube P will drop in potential due to current flow through its anode resistor 20, and thus a negative impulse will be impressed on pulse line 14. This negative impulse will be impressed on the anodes of trigger tubes 0, 1, 9 through condensers 15. Assuming the tube 0 of this chain in the conducting state with the others in the non-conducting state-when this impulse arrives at its anode, the impulse will convert tube 0 to the non-conducting state. Through condensers 15 and 16, in series the negative impulse on pulse line 14 is applied to the grids ofv all the tubes in the chain, and tube 0 is prevented from reigniting by the negative impulse on its grid through the associated condenser 16. Thus the anode of tube 0 rises to the potential of the anode supply and produces a positive transfer pulse through associated condenser 16, and current limiting resistor 17 at the grid of the succeeding tube 1. The rise in potential on the grid of tube 1 converts it from the non-conducting to the conducting state. This conversion produces a negative pulse from its anode through associated condenser 15, which is transmitted over pulse line 14 to the anode of tube P to convert tube P back from a conducting to a non-conducting state to await the application at its grid of the next of the series of impulses to be counted. When the next impulse arrives the cycle is repeated with a resulting extinguishing of tube 1 and igniting of the next tube 2 (not shown). It is thus apparent that the particular tube in the chain which is ignited will indicate the number of impulses which have been applied to the grid of impulse tube P. Obviously, with ten trigger tubes as shown only nine impulses can be counted with certainty, since with ten impulses tube 0 will be ignited at the end of the count. To overcome this a carry over circuit may be provided. This may be a second counting system similar to the one disclosed and having its input connected to output terminal 18. This will indicate every tenth impulse. A second carry over circuit may be connected to the output of the first carry over circuit, if desired, to indicate every hundredth impulse.

Thus a counting system is provided which furnishes im-' Since the positive transfer pulse applied to the grids of I tubes 0, 1, 9, should be of longer duration than the negative impulse on the pulse line 14, the time constant of condenser 16 and resistor 21 should be greater than that of condenser 15 and resistor 12. Suitable values of the circuit constants are tabulated below:

Resistor 12 meg. .1 Resistor 21 meg 1 Resistor 17 meg 2 Resistor 20 meg .5 Condenser 15 f .000 Condenser 16 ,u.f .0003

The invention is to be limited only by the appended claims.

I claim:

1. A counting system for counting electrical impulses comprising a pulsing circuit and a chain of trigger circuits, the pulsing circuit and each trigger circuit including a tube having an ionizable substance, a cathode, a grid and an anode, the anodes being normally maintained at positive potential and the grids at negative potential with respect to the cathodes, the several tubes having a conducting and a non-conducting state of stability, the tube in said pulsing circuit being normally in the non-conducting state and having its anode connected through a pulse line to the several anodes of the tubes of said trigger circuits and in response to a positive impulse at its grid being converted to the conducting state to apply a negative impulse to the said several anodes to thereby convert any tube in said chain which is in the conducting state to the nonconducting state, a transfer circuit to apply to the grid of the next succeeding tube in said chain a positive transfer impulse to convert said tube to the conducting state, and thereby produce a negative pulse at its anode to reconvert over said pulse line the tube in said pulsing circuit to the non-conducting state.

2. A counting system for counting electrical impulses comprising a pulsing circuit and a chain of trigger circuits, the pulsing circuit and each trigger circuit including a tube having an ionizable substance, a cathode, a grid and an anode, the anodes being normally maintained at a positive potential and the grids at a negative potential with respect to the cathodes, the several tubes having a conducting and a non-conducting state of stability, the tube in said pulsing circuit and the several tubes less one in said chain of trigger circuits being normally in the non-conducting state, said one tube being normally in the conducting state, the anode of the tube in said pulsing circuit being connected through a pulse line with the several anodes of the tubes in said trigger circuits and in response to a positive impulse at its grid to be converted to the conducting state to apply a negative impulse to the said several anodes to thereby convert said one tube to the nonconducting state, a transfer circuit to apply to the grid of the next succeeding tube in said chain a positive transfer impulse from the anode of said one tube to convert said succeeding tube to the conducting state and produce a negative pulse at its anode to be transmitted over said pulse line and applied to the anode of the tube in said pulsing circuit to reconvert said last mentioned tube to the non-conducting state.

3. A pulsing circuit for applying uniform rectangular voltage pulses to an electronic counter comprising a source of positive voltage pulses to be counted, a gaseous electron discharge tube having an anode, a cathode, and a control grid, means applying potentials to said tube to bias said tube to non-conduction, means applying said pulses to said control grid to initiate conduction in said tube thereby reducing the anode potential thereof, means applying the voltage drop so initiated to the input of said counter, and means applying a negative pulse from said counter to the anode of said tube to terminate said state of conduction and said rectangular voltage pulse.

4. In combination with an electron tube ring type counter, a pulsing circuit for applying uniform rectangular voltage pulses to said counter in response to input pulses to be counted comprising, a gaseous electron discharge tube having an anode, a cathode and a control grid, means applying potentials to said gaseous electron discharge tube to bias said tube to be normally non-conducting, the anode circuit of said tube including a load resistor, means applying said pulses to be counted to said control grid to initiate conduction in said tube, the conduction of said tube thereby producing a voltage drop across said resistor, means coupling the anode of said tube to the input circuit of said counter to initiate a count therein, and means to feed back a pulse from said gaseous electron discharge counter to terminate the conduction of said tube.

5. In combination with an electron tube ring type counter, a pulsing circuit for applying uniform rectangular voltage pulses to said counter in response to input pulses to be counted comprising, a gaseous electron discharge tube having an anode, a cathode and a control grid, means applying potentials to said gaseous electron discharge tube to bias said tube to be normally non-conducting, the anode circuit of said tube including a load resistor, means applying said pulses to be counted to said control grid to initiate conduction in said tube, the conduction of said tube thereby producing a voltage drop across said resistor, a pulse line coupling the anode of said tube to the input circuit of said counter to initiate a count therein in response to said voltage drop, and means in said counter to feed back a negative voltage pulse from said counter along said pulse line to the anode of said tube to terminate the conduction thereof.

6. In combination, a counting ring of grid controlled gaseous discharge tubes wherein said tubes are electrostatically coupled in an endless series anode to control grid and wherein the anodes are all coupled electrostatically to a common input conductor whereby each negative pulse impressed thereon acts to render any conducting tube nonconducting, which action of extinguishment gives rise to a positive impulse rendering the next tube of the ring conducting, a pulsing circuit for applying uniform rectangular voltage pulses to said counter in response to positive input voltage pulses to be counted comprising, a grid controlled gaseous electron discharge tube normally biased to be nonconducting, a load resistor in series with said tube, means coupling said tube to said input conductor of said counting ring, means applying said positive input voltage pulses to be counted to the control grid of said tube in said pulsing circuit to initiate conduction therein, thereby producing a voltage drop across said load resistor to actuate said counting ring, and means responsive to the shift of conduction in the tubes of said counting ring to apply a negative voltage pulse to said common conductor to terminate the conduction of said gaseous discharge tube in said pulsing circuit.

References Cited in the file of this patent UNITED STATES PATENTS 2,224,832 Pfister Dec. 10, 1940 2,398,772 Cone et al Apr. 23, 1946 2,399,473 Desch et al. Apr. 30, 1946 2,404,918 Overbeck July 30, 1946 2,405,095 Mumma July 30, 1946 2,442,304 Mayle May 25, 1948 

